title: HLA-G is differentially expressed in thyroid tissues.
abstract: BACKGROUND
  HLA-G is a nonclassical major histocompatibility complex molecule that has well-recognized immunomodulatory properties. The expression of HLA-G in tumor cells has been considered to be detrimental, permitting tumor spreading and decreased survival. We evaluated the expression of HLA-G in histologically normal thyroid tissue, goiter, and benign and malignant thyroid tumors, and studied the relationship between HLA-G expression and patient clinical variables.
  
  
  METHODS
  The immunohistochemistry expression of HLA-G was performed on 72 specimens of papillary thyroid carcinoma (PTC), 19 follicular thyroid carcinomas (FTC), 22 follicular adenomas (FA), 22 colloid goiters (CG), and 14 histologically normal thyroid glands (NT). The percentage of HLA-G staining was graded from absent (-) to intense (+++).
  
  
  RESULTS
  HLA-G was faintly expressed in areas of hyperplasia in NT and CG. In PTC, FTC, and FA, the percentage of cell staining was significantly higher than in NT and CG (p<0.001 for each comparison). The tumor area with HLA-G expression was greater in FTC (p=0.0059) and PTC (p=0.0330) compared to FA. According to the magnitude of HLA-G staining, PTC tumors >1 cm exhibited increased HLA-G staining when compared to smaller tumors (p=0.03). Aggressive histologic subtypes of PTC have a higher median stained tumor area. No association was found between HLA-G expression and tumoral staging or patient disease-free survival.
  
  
  CONCLUSIONS
  The gradual increase of HLA-G expression from hyperplasia to carcinomas, and the association of strong HLA staining with some variables implicated in poor prognosis corroborate the unfavorable role of HLA-G in tumor thyroid cells, inhibiting cytotoxic immune system cells and facilitating tumor evasion and progression.
authors.affiliation: 1 Division of Endocrinology & Metabolism, University of São Paulo , São Paulo, Brazil .
authors.forename: Nathalie Lobo
authors.initials: NL
authors.lastname: de Figueiredo Feitosa
authors.forename: Janaina Cristina de Oliveira
authors.initials: JC
authors.lastname: Crispim
authors.forename: Bruna Riedo
authors.initials: BR
authors.lastname: Zanetti
authors.forename: Patrícia Kunzle Ribeiro
authors.initials: PK
authors.lastname: Magalhães
authors.forename: Christiane Pienna
authors.initials: CP
authors.lastname: Soares
authors.forename: Edson Garcia
authors.initials: EG
authors.lastname: Soares
authors.forename: Luciano
authors.initials: L
authors.lastname: Neder
authors.forename: Eduardo Antonio
authors.initials: EA
authors.lastname: Donadi
authors.forename: Léa Maria Zanini
authors.initials: LM
authors.lastname: Maciel
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000378:metabolism* / Q000473:pathology; D000236:Adenoma / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D002291:Carcinoma, Papillary / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006042:Goiter / Q000378:metabolism* / Q000473:pathology; D059951:HLA-G Antigens / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D013961:Thyroid Gland / Q000378:metabolism* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D059951:HLA-G Antigens